This invention relates generally to irrigation sprinklers, and more particularly to an improved irrigation sprinkler of the type having an inlet control valve for controlling connection of the sprinkler to a water supply line. The improved sprinkler of the present invention includes a removable valve seat for the inlet control valve, wherein the valve seat is combined with an inlet filter screen and is adapted for quick and easy removal from the top of a sprinkler case or housing.
Irrigation sprinklers are well known in the art for use in supplying irrigating water over a circular or part-circular ground area around the sprinkler. Typically, such sprinklers employ single or multiple outlet spray nozzles through which the water is ejected upwardly and radially outwardly from the sprinkler case, and include rotary drive means for rotating the spray nozzle, such as an impact drive arm assembly which interrupts the stream from the nozzle, or a water operated drive motor such as a ball drive, gear drive or turbine drive apparatus mounted within the sprinkler case. In many sprinklers, the sprinkler also includes a pop-up mechanism wherein the spray nozzle is attached to the upper end of a tubular riser mounted within the sprinkler case for pressure responsive movement between an elevated position above the sprinkler case during normal operation and a retracted position disposed substantially within the case when the sprinkler is not in operation. In a common installation, the sprinkler case has a lower end thereof connected to an underground water supply line, with the sprinkler case partially buried to position the upper end thereof substantially at ground level.
In many irrigation sprinklers of the type described above, an inlet control valve is provided at the lower end of the sprinkler case to control water inflow from the water supply line. In one typical form, as shown and described in U.S. Pat. No. 4,681,259, the inlet control valve comprises a pressure responsive valve assembly designed to prevent water inflow to the sprinkler case unless and until the water pressure rises to a predetermined minimum threshold pressure level. As a result, when the water supply is initially turned on, the inlet control valve prevents water flow to the sprinkler until the water pressure rises sufficiently to provide proper sprinkler pop-up and rotary drive operation. Similarly, when the water supply is turned off, the inlet control valve prevents water inflow to the sprinkler case when the line pressure falls below the minimum threshold level for proper sprinkler operation. Accordingly, undesirable flow of water through the sprinkler at low pressure and resultant puddling in the vicinity of the sprinkler is avoided. This problem can be significant in a system of sprinklers connected to a common supply line, wherein residual water remaining within the supply line would otherwise drain to and through sprinklers located at relatively low elevational positions.
A filter screen is normally mounted at the upstream side of the inlet control valve to trap and retain small rocks and other particulate debris and thereby prevent entry thereof into the sprinkler case. Such particulate matter, if allowed to flow into the sprinkler case, could interfere with proper sprinkler operation by jamming or damaging mechanical components of the sprinkler. However debris collected by the filter screen tends to accumulate over a period of time, and ultimately may accumulate to a point where the collected debris represents a sufficient pressure drop obstruction to prevent proper sprinkler operation. When this occurs, the filter screen must be accessed in order to clean and flush the collected debris therefrom. In the past, significant labor and time has been required to excavate and disassemble the sprinkler case from the buried water supply line to permit access to the filter screen at the lower end of the sprinkler case, followed by re-assembly of the sprinkler to the underground supply line.
Another problem encountered with irrigation sprinklers involves pitting and wear of the valve seat included as part of the inlet control valve, resulting in undesired low pressure water leakage through the sprinkler case when the inlet control valve is closed. In this regard, the valve seat for the inlet control valve normally comprises a plastic surface formed or otherwise mounted on the plastic molded sprinkler case. Over time, small pebbles and grit such as rust particles and the like of a sufficiently small size to pass through the filter screen can impact and damage the valve seat. Attempts to prevent such damage by using a smaller mesh filter screen unfortunately result in a more frequent clogging of the filter screen. When valve seat damage occurs, it has been necessary to excavate and disassemble the sprinkler case from the buried water supply line for appropriate replacement, typically by installation of a new sprinkler case. Once again, such remedial action is a time consuming and labor intensive process.
There exists, therefore, a need for an improved mounting arrangement for a valve seat of a sprinkler inlet control valve, and for an inlet filter screen associated therewith, to provide improved and facilitated access to the valve seat and filter screen in the event that service or replacement is required, without requiring the sprinkler case to be disassembled from the associated water supply line or otherwise removed from the ground. The present invention fulfills these needs and provides further related advantages.